R01 return code: Insufficient Funds

R01 is the return reason code Insufficient Funds. The balance can't cover the debit.

It is sent by the RDFI as a return entry: the original entry goes back to the ODFI with an addenda record carrying R01, and the ODFI passes the return on to the Originator.

• The available balance was below the debit amount when the RDFI posted the entry.
• A deposit the Receiver was counting on had not arrived or had not cleared yet.
• The Receiver expected the debit on another day than the effective date it carried.

Available to the ODFI by opening of business on the 2nd banking day after the settlement date of the original entry.

Banking days are the Federal Reserve’s business days: weekends and Fed holidays don’t count, so a holiday in the window pushes the deadline out by a day.

• The Rules let you reinitiate the debit at most twice after this return (three presentments in all), within 180 days of the original entry’s settlement date, with RETRY PYMT in the Company Entry Description.
• If the retries fail too, collect another way and ask the Receiver to confirm the account to use.

A return is the original entry detail record (type 6) sent back with a return transaction code — 21 or 26 for a checking account, 31 or 36 for savings (21 and 31 return a credit, 26 and 36 a debit) — the original amount, and an addenda record of type 99 that carries the reason. The batch keeps the original entry’s SEC code.

To read a return file record by record, open the file in NACHA Navigator, a free sister site that parses NACHA files in your browser without uploading them.

The code table on this page is the one behind the REST API and the MCP server, so a script or an AI agent gets the same answer as JSON. No key and no account.

curl -s 'https://payopskit.com/api/v1/codes/R01?set=ach-return'

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "lookup_payment_code",
    "arguments": {
      "code": "R01",
      "set": "ach-return"
    }
  }
}

{
  "code": "R01",
  "set": "ach-return",
  "found": true,
  "matches": [
    {
      "set": "ach-return",
      "code": "R01",
      "name": "Insufficient Funds",
      "description": "The balance can't cover the debit.",
      "details": {
        "category": "return",
        "timeframe": "Available to the ODFI by opening of business on the 2nd banking day after the settlement date of the original entry",
        "timeframeKind": "banking-days",
        "timeframeDays": 2,
        "timeframeFrom": "original-settlement",
        "account": "any",
        "accountNote": null,
        "writtenStatement": false,
        "initiatedBy": "RDFI",
        "note": null,
        "effectiveFrom": null,
        "upcomingChange": null,
        "caveat": null
      }
    }
  ]
}

The deadline for a settlement date: GET /api/v1/ach/return-deadline?settlement_date=2026-11-25&code=R01 or the MCP tool ach_return_deadline.

• R09Uncollected Funds
• R08Payment Stopped
• R02Account Closed

All ACH return codes, R01 to R85